These skimmers make me a little more nervous than ATM ones, since they are a replacement for the existing hardware on the pump. In other words the crooks swap out the original cardreader (on the left) with the modified one (on the right). This gives the devices power from the pump, and being bluetooth enabled allows wireless data dumps. I just wonder when they crooks got the time to “replace” the units. Given the locks on the pumps are typically easy to pick, it still would take time and seem strange to me if someone just opened up a pump and swapped the innards.
http://krebsonsecurity.com/2013/07/dont-get-sucker-pumped/